Greywater is a term used for an intermediate class of domestic wastewater, typically coming from showers, diswashing, laundry, and other ‘light duty’ applications that do not put the ‘bad stuff’ into water (like toilets).

So greywater does not really require the level of wastewater treatment that ‘blackwater’ does.

<li><a href="http://www.oasisdesign.net/greywater/">Oasis Design</a> is an authoritative site on greywater for residential applications.</li>